Offset rotary printing machines usually have an ink trough from which ink is applied over a plurality of ink transfer and distribution rollers, some of which may be axially oscillating to provide for fine distribution of the ink, for subsequent application to the plate cylinder of the printing machine.
The quality of the resulting print depends substantially on the fineness of the ink applied from the ink trough through the respective distribution rollers or cylinders, which form an ink train, to the ink transfer rollers and hence to the plate cylinder. To obtain the desired ink film, continuous transfer of ink is usually used. The wetting liquid, typically water, used in the offset process may form an emulsion with the ink. It has been proposed to decrease the formation of an ink-water emulsion by increasing the surface of the rollers of the ink train. To provide a sufficient surface--for example as described in German Published Patent Application DE-AS No. 20 12 232-to utilize a fairly large number of ink transfer rollers, journaled in respective bearings at their axial ends, some of which may be axially oscillating. This system is expensive to manufacture and, due to the continuous frictional contact between the ink-coated roller, requires additional operating energy.